Axcelis Technologies, assignee of the present invention, sells products for treatment of silicon wafers during Integrated Circuit fabrication. One such product or tool creates an ion beam that modifies the physical properties of wafers that are placed into the ion beam. This process can be used, for example, to dope the silicon from which the untreated wafer is made to produce a semiconductor material. Controlled use of masking with resist materials prior to ion implantation as well as layering of different dopant patterns within the wafer produce an integrated circuit for use in one of a myriad of applications.
Prior art U.S. Pat. No. 5,177,366 to King et al and U.S. Pat. No. 5,091,655 to Dykstra et al. discuss methods of using two pair of electrostatic scanning electrodes to generate parallel ion beams. The '366 patent concerns an ion beam implantation system wherein an ion beam is controllably deflected from an initial trajectory as it passes through spaced parallel plates that are biased by a control circuit. Once deflected, the ion beam passes through electrodes positioned along a beam travel path that both re-deflect the once-deflected ion beam and accelerate the ions to a desired final energy. Ions within the beam exit the accelerator and impact a work-piece at a uniform, controlled impact angle due to ion focusing in a scanning plane and an orthogonal cross plane.
The '655 patent relates to an ion beam that is controllably deflected from an initial trajectory as it passes through spaced parallel plates that are biased by a control circuit. Once deflected, the ion beam enters an accelerator that both re-deflects the once deflected ion beam and accelerates the ions to a desired final energy. When the beam exits the accelerator it moves along a trajectory that impacts a work-piece. Ions making up the ion beam all impact the work-piece at a uniform, controlled impact angle.
A printed publication entitled “The Nissin NH-20SP medium-current ion implanter” to Nagai et al describes a medium current ion implanter. The implanter has a pair of so-called kickback electrodes H2 that compensate for side to side scanning introduced by an initial set of electrodes. The sweep-voltage waveform applied to the H1 and H2 electrodes is generated by a digital-waveform generator, or a waveform controller.